$sudo aptitude install x-window-system-core gnome-core
$aptitude install xubuntu-desktop
$apt-get install gdm
$/etc/init.d/gdm start
$rdesktop 143.210.123.456
$rdesktop -u john 143.210.123.456
$rdesktop -u john -fP 143.210.123.456
$rdesktop -u john -g 100% -PKD 143.210.123.456
-r disk:doc=/home/john/Documents,pic=/home/john/Pictures
-r sound:local
-k ko
If you install Linux O.S. as (Guest Operating System) on top of your existing windows machine using VMware virtual Server check here, Next step is to copy R12/11i/oracle software from windows machine to VMware Linux O.S.
Steps mentioned below are to share folder on Windows (host o.s.) and access it from Linux (guest o.s.)
A. Share folder on Windows Machine
1. Check your windows Workgroup name >> Right click on My Computer and click on Properties
2. Click on Computer Name tab and check Workgroup Name
3. Next step is to share folder on windows machine
Right click on Folder which you wish to share and access from Linux Machine and click on Properties
4. Click on Sharing taband select Share this folder on the network
.
B. Changes on Linux Virtual Machine (Guest Operating System)
1. During Linux installation, select Customize software packages to be installed
2. Click on Details against Server Configuration Tools
3. Select system-config-samba - Samba Server Configuration Tool
If you don’t want to select Samba Server specifically, then select everything
3. select Everything from package list
After Linux installation, modify samba server configuration
Open /etc/samba/smb.conf and make following changes
1. workgroup = [change it to your windows workgroup] like
workgroup = WORKGROUP
.
2. server string = Samba Server [name] like
server string = Samba Server myLinux Server
3. Uncomment entry like hosts allow = [windows IP address]
to check your windows machine use “ipconfig”
hosts allow = [your windows IP address here]
like
hosts allow = 192.168.1.2 (Please change above IP to your windows IP)
4. uncomment these two lines by removing ; (semicolon) from below two lines
encrypt passwords = yes
smb passwd file = /etc/samba/smbpasswd
5. At end of file uncomment following files
[myshare]
comment = My Linux share
path = /BI
valid users = oracle
public = no
writable = no
printable = no
create mask = 0765
Here “path = /BI” is windows share name and ”valid users= oracle” is user on windows machine.
6. Restart samba server using
/etc/init.d/service smb stop
/etc/init.d/service smb start
7. Create directory on Linux to view windows shared folder
mkdir -p /stage/WinServer
8. Mount Windows share foler on linux using
mount -t smbfs -o username=sreejith, password=[password] //192.168.1.2/BI /stage/WinServer
or
mount -t smbfs -o username=sreejith //Computer name/Temp /mnt/shared
above password is windows machine password for user atul (replace your windows username and password)
192.168.1.2 is IP address of windows machine ( Change 192.168.1.2 to your windows IP address and Verify that you can ping windows IP from Linux machine)
BI is shared folder name on windows
and /stage/WinServer is folder name on Linux
9. Access windows share on linux using
cd /stageWinServer
ls
other ways of using samba share
1. Using samba client
$smbclient //computername/Temp -U sreejith
smb:\>help
2. Using samba mount
$smnbmount //computername/Temp mnt/shared
to unmount
$smbumount mnt/shared
If you've got a website that's heavy on your web server, you might want to run some processes like generating thumbnails or enriching data in the background. This way it can not interfere with the user interface. Linux has a great program for this called cron. It allows tasks to be automatically run in the background at regular intervals. You could also use it to automatically create backups, synchronize files, schedule updates, and much more. Welcome to the wonderful world of crontab.
The crontab (cron derives from chronos, Greek for time; tab stands for table) command, found in Unix and Unix-like operating systems, is used to schedule commands to be executed periodically. To see what crontabs are currently running on your system, you can open a terminal and run:
sudo crontab -l
To edit the list of cronjobs you can run:
sudo crontab -e
This wil open a the default editor (could be vi or pico, if you want you can change the default editor) to let us manipulate the crontab. If you save and exit the editor, all your cronjobs are saved into crontab. Cronjobs are written in the following format:
* * * * * /bin/execute/this/script.sh
Scheduling explained
As you can see there are 5 stars. The stars represent different date parts in the following order:
1. minute (from 0 to 59)
2. hour (from 0 to 23)
3. day of month (from 1 to 31)
4. month (from 1 to 12)
5. day of week (from 0 to 6) (0=Sunday)
Execute every minute
If you leave the star, or asterisk, it means every. Maybe that's a bit unclear. Let's use the the previous example again:
* * * * * /bin/execute/this/script.sh
They are all still asterisks! So this means execute /bin/execute/this/script.sh:
1. every minute
2. of every hour
3. of every day of the month
4. of every month
5. and every day in the week.
In short: This script is being executed every minute. Without exception.
Execute every Friday 1AM
So if we want to schedule the script to run at 1AM every Friday, we would need the following cronjob:
0 1 * * 5 /bin/execute/this/script.sh
Get it? The script is now being executed when the system clock hits:
1. minute: 0
2. of hour: 1
3. of day of month: * (every day of month)
4. of month: * (every month)
5. and weekday: 5 (=Friday)
Execute on workdays 1AM
So if we want to schedule the script to Monday till Friday at 1 AM, we would need the following cronjob:
0 1 * * 1-5 /bin/execute/this/script.sh
Get it? The script is now being executed when the system clock hits:
1. minute: 0
2. of hour: 1
3. of day of month: * (every day of month)
4. of month: * (every month)
5. and weekday: 1-5 (=Monday til Friday)
Execute 10 past after every hour on the 1st of every month
Here's another one, just for practicing
10 * 1 * * /bin/execute/this/script.sh
Fair enough, it takes some getting used to, but it offers great flexibility.
Neat scheduling tricks
What if you'd want to run something every 10 minutes? Well you could do this:
0,10,20,30,40,50 * * * * /bin/execute/this/script.sh
But crontab allows you to do this as well:
*/10 * * * * /bin/execute/this/script.sh
Which will do exactly the same. Can you do the the math? ;)
Special words
If you use the first (minute) field, you can also put in a keyword instead of a number:
@reboot Run once, at startup
@yearly Run once a year "0 0 1 1 *"
@annually (same as @yearly)
@monthly Run once a month "0 0 1 * *"
@weekly Run once a week "0 0 * * 0"
@daily Run once a day "0 0 * * *"
@midnight same as @daily)
@hourly Run once an hour "0 * * * *
Leave the rest of the fields empty so this would be valid:
@daily /bin/execute/this/script.sh
Storing the crontab output
By default cron saves the output of /bin/execute/this/script.sh in the user's mailbox (root in this case). But it's prettier if the output is saved in a separate logfile. Here's how:
*/10 * * * * /bin/execute/this/script.sh 2>&1 >> /var/log/script_output.log
Explained
Linux can report on different levels. There's standard output (STDOUT) and standard errors (STDERR). STDOUT is marked 1, STDERR is marked 2. So the following statement tells Linux to store STDERR in STDOUT as well, creating one datastream for messages & errors:
2>&1
Now that we have 1 output stream, we can pour it into a file. Where > will overwrite the file, >> will append to the file. In this case we'd like to to append:
>> /var/log/script_output.log
Mailing the crontab output
By default cron saves the output in the user's mailbox (root in this case) on the local system. But you can also configure crontab to forward all output to a real email address by starting your crontab with the following line:
MAILTO="yourname@yourdomain.com"
Mailing the crontab output of just one cronjob
If you'd rather receive only one cronjob's output in your mail, make sure this package is installed:
aptitude install mailx
And change the cronjob like this:
*/10 * * * * /bin/execute/this/script.sh 2>&1 | mail -s "Cronjob ouput" yourname@yourdomain.com
Trashing the crontab output
Now that's easy:
*/10 * * * * /bin/execute/this/script.sh 2>&1 > /dev/null
Just pipe all the output to the null device, also known as the black hole. On Unix-like operating systems, /dev/null is a special file that discards all data written to it.
When a file is created, its permissions are set by default depending on the umask setting. This value is usually set for all users in /etc/profile and can be obtained by typing:
umask
The default umask value is usually 022. It is an octal number which indicates what rights will be removed by default to all new files. For instance, 022 indicates that write permissions will not be given to group and other.
By default, and with a umask of 000, files get mode 666 and directories get mode 777. As a result, with a default umask value of 022, newly created files get a default mode 644 (666 - 022 = 644) and directories get a default mode 755 (777 - 022 = 755).
In order to change the umask value, simply use the umask command and give it an octal number. For instance, if you want all new directories to get permissions rwxr-xr--- and files to get permissions rw-r----- by default (modes 750 and 640), you'll need to use a umask value which removes all rights to other, and write permissions to the group : 027. The command to use is:
$ umask 027
The following example explains the steps needed to set umask for permissions 700 for user files. The idea very simply only user is allowed to read or write file.
Default Permissions: 777
Subtract umask value: 077 (-)
Allowed Permissions: 700
$ umask 077
$ touch file.txt
$ ls -l file.txt
Output:-
rw------- 1 vivek vivek 0 2007-02-01 02:21 file.txt
Categories: None
$ sudo passwd root
[sudo] password for existing user
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Later if you don’t want to use su anymore, you can lock the root user password using one of the methods shown below
$ sudo passwd -l root( or )
$ sudo usermod -p '!' root
